Prevalence and antimicrobial resistance of Enterobacterales bacteria isolated from retail food in Poland.

Abstract

Introduction: The prevalence of potentially pathogenic microorganisms in different foods is widely researched. The aim of this study was to investigate the prevalence and antimicrobial resistance of selected Enterobacterales species isolated from retail food of animal origin in Poland.

Material and methods: Cold cuts, cold-smoked fish and cheeses making 194 samples were tested with the ISO horizontal method for the detection of Enterobacteriaceae, and then Enterobacterales isolates were identified using matrix-assisted laser desorption/ionisation-time of flight mass spectrometry (MALDI-TOF). The isolates' antimicrobial susceptibility was determined using the minimal inhibitory concentration method.

Results: Enterobacterales were detected in 159 (82.0%) samples, from which 226 bacterial isolates were recovered. Six bacterial species accounted for 65.9% of Enterobacterales isolates: Escherichia coli (n = 41), Enterobacter cloacae (n = 26), Hafnia alvei (n = 25), Citrobacter spp. (n = 20), Serratia liquefaciens (n = 20) and Klebsiella oxytoca (n = 17). The isolated E. coli strains showed low resistance to seven antimicrobials. E. cloacae isolates were mostly resistant to ampicillin (76.9%) and azithromycin (38.5%), S. liquefaciens to colistin (100%) and H. alvei strains to colistin (96.0%) and ampicillin (60.0%). The majority of K. oxytoca isolates (70.6%) were resistant to ampicillin, whereas only five Citrobacter isolates were. Twenty of the total pool of isolates (8.8%) were defined as multidrug resistant.

Conclusion: Retail food of animal origin can be contaminated with various species of Enterobacterales, including microorganisms pathogenic to humans as well as others resistant to commonly used antimicrobials.